Celestia

Celestia is an OpenGL-based 3D space simulation for Unix and Win32 that lets you travel through the solar system, to the stars, and even beyond the galaxy. Visit over 100,000 stars, 100 solar system bodies, and all known extrasolar planets.

Recent releases

Release Notes: Major improvements were made to 3D visuals,
including realistic scattering atmospheres, new
photometric functions, and improved rendering of
orbit paths. Support for the DE405 ephemeris and
NASA/JPL's SPICE system was added in order to
improve accuracy for demanding applications such
as spaceflight trajectory visualization. Galaxy,
star, and planet catalogs were all updated with
the latest data.

Release Notes: A brand new 3D model and complete trajectory of the
Cassini mission to Saturn is included, so that you can follow
the spacecraft from launch through its four years in orbit
around Saturn. This new version also supports a new 3D file
format for storing higher quality models of irregular objects.
The data files have been updated with the latest extrasolar
planet and solar system discoveries. There are new scripting
commands, extended character set support, and
improvements to rendering speed and quality.

Release Notes: This is a major update from 1.2.5. The most significant addition is the multiview feature, which allows several simultaneous views of an event from different locations. There are also new keyboard commands for handling light time delay, improved browser integration, a more convenient structure for add-ons, better graphics card support, and fixes for some nasty bugs that plagued version 1.2.5.

Release Notes: Version 1.2.5 of Celestia adds a KDE frontend for Linux, rendering of comet tails, and a host of bugfixes. The accuracy of orbital calculations has been improved to the point where you can observe mutual phenomena of the Galilean moons, spacecraft encounters with planets, planetary occultations, and many other celestial phenomena. Other additions include auto magnitude (based on field of view), distance filtering of stars, ring shadows, and new Web features.